Efforts have been made in the past to form carding surfaces wherein pyramidal teeth have a sharpened leading edge. Such a structure is contemplated in British Pat. No. 974,186, published Nov. 4, 1964, however, such surface was formed by cutting or grinding a surface with a gang cutting device. Such a configuration would be wholly impractical from the standpoint of manufacture in the volume necessary for use in connection with most carding elements used in practical operation. In Swiss Pat. No. 464,349, published Feb. 28, 1969, teeth of varying depth are alternately laterally deflected. It has heretofore been contemplated that saw blades may be manufactured by punching a metallic strip and such has been illustrated in U.S. Pat. No. 2,510,462. This patent contemplates feeding the blade for regular stopping momentarily for carrying out the punching operation and the applicable disclosure of this patent is incorporated herein and made a part hereof by reference. Saw blades have also been contemplated having teeth with sharpened leading edges such as illustrated in U.S. Pat. No. 3,331,265. This patent contemplates the formation of teeth by a milling operation and results in a simple angle forming the leading edge of the saw teeth.
The metallic wire card clothing used in conventional carding operations and placed upon conventional carding elements such as cylinders, licker-ins, doffers, flats, and the like have teeth which are placed therein by means of a punch and die. The teeth are slightly recessed or beveled toward the die side of the tooth as normally results from the punching operation. Such a punching phenomenon in connection with saw blades is shown in U.S. Pat. No. 3,540,317. The teeth are customarily formed in profile wire having a base and an upwardly tapering rolled portion extending therefrom in which the teeth are formed. In conventional methods of manufacture, the teeth of metallic card clothing are formed by a punch driven at right angles, both longitudinally and transversely, to the direction of travel of the profile wire. The teeth thus have sides as well as a transverse leading edge together with a transverse trailing edge.
It is desirable that the teeth present a thinner forward working surface with thinner points in order to reduce nep count, but if the point is too thin, wear results in excessive regrinding and resetting. There may be a tendency for the tip of the tooth to twist away from the die side. A conventional shouldered configuration may be employed herein but a wide variety of configurations may be employed so long as a base support is provided for the teeth.
It is an important object of the present invention to provide a sharpened surface along the leading edge of the teeth of metallic card clothing.
It has been found that by utilizing such a configuration, the nep count may be reduced and unexpectedly that the required amount of opposed carding surface may be reduced and such lesser amount of surface set at a greater distance from the cylinder thus reducing wear and minimizing the possibility of facing of the clothing of the cylinder and carding surface. The wider settings reduce the tendency for fiber damage. All settings between such clothed surfaces may be increased. Moreover, considerably greater production speeds may be achieved without sacrifice of these advantages.
A further object of the present invention is to provide a carding surface where the teeth retain their sharpness and carding effectiveness after considerable wear or grinding.